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Classifications

B—PERFORMING OPERATIONS; TRANSPORTING

B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS

B41N—PRINTING PLATES OR FOILS; MATERIALS FOR SURFACES USED IN PRINTING MACHINES FOR PRINTING, INKING, DAMPING, OR THE LIKE; PREPARING SUCH SURFACES FOR USE AND CONSERVING THEM In this subclass the COPES System is used

B41N1/083—Printing plates or foils; Materials therefor metallic for lithographic printing made of aluminium or aluminium alloys or having such surface layers

Abstract

PURPOSE:To enhance tensile strength and fatigue strength, by using a base obtained by subjecting an aluminum alloy plate having a predetermined alloy composition to a mechanical roughening treatment, an acidic or alkaline solution treatment and a predetermine electrochemical roughening treatment. CONSTITUTION:An aluminum alloy plate containing 0.35-0.9wt% of Mg, 0.05-0.5wt% of Fe, up to 0.2wt% of Si and up to 0.05wt% of Cu, the remainder being Al and unavoidable impurities, is mechanically roughened, is treated with an acidic or alkaline solution, and is electrochemically roughened in an electrolytic solution based on hydrochloric acid or nitric acid to obtain a base. The mechanical roughening may be carried out by a graining method such as a wire brush graining method in which the surface of aluminum is scratched by metallic wires. A photosensitive substance is applied to the base to provide a photosensitive layer, whereby a photosensitive planographic plate can be obtained.